Dry kiln



March 13, 1928.

F M. CREIGHTON ET AL DRY KILN Patented Mar. 13, 1928.

UNITED STATES 1,662,807 PATENT OFFICE.-

FRANK'M. GREIGHTON, OF AMERICUS, GEORGIA, AND WILLIAM E. GRAY, OFMEMPHIS,

TENNESSEE, ASSIGNORS TO MOORE DRY KILN COMPANY, OF JACKSONVILLE, FLOR-IDA, A CORPORATION or FLORIDA.

' DRY KILN.

Application filed April 13, 1926. Serial No. 101,761.

Our invention relates to an improvement in dry kilns and this particularinvention pertains to a kiln of so-called progressive t The fundamentalobject is to provide a kiln in which advantage is taken of the naturalcirculatory course'of the air currents, and in this connection toprovide means calculated to accelerate this natural motion of the airthrough the kiln.

This particular invention includes a heating system, humidifying means,arranged to suit the requirements, means for reheating andre-conditioning the air on its return to the drying chamber, from whichmeans it is discharged into the kiln at any desired prearranged point,in an upward direction through the drying chamber, together withauxiliary means for accelerating the natural passage and courseOfclICllliltlOIl of the air.

More specifically speaking, this invention consists'in -a drying chamberwith suitable heating means andme-ans for humidifying the air, incombination with air intakes andv return conduits extending inwardlyfrom the intakes and discharging upwardly into the drying chamber, in adirection suited to the natural course of the air currents from what istermed the dry end of the kiln, in the direction of the green end wherethere is more moisture in the material being treated and a greateramount of humidity in the air, mechanical means being employed at thedry end to accelerate this natural course or cycle of air currents.

In the accompanying drawings:

Figure 1 isa vertical longitudinal section through an illustrative formof my invention, and

' Figure 2-is a horizontal section.

A represents the drying chamber of the kiln and the numerals 1 representsome approved formof roof ventilators.

A heating system 2 extends long1tud1- nally of the bottom of the kilnand preferably below the rails.3., Various forms of pipin for theheating system may be employs although it is desirable to have anexcessive heat at the dry or. right-hand end of the kiln as! indicatedby the three leads of pipes at that end. 7

Doors 4 are provided. at opposite ends and therails 3 usuallyslope-downwardly from the wet end toward the dry end of the kiln,

they being supported on pillars 5, or other suitable foundation.

An air intake 6 is located at some point in the bottom of the kiln at ornear the greenend, preferably just inside the door. This is usuallycovered over by a screen 7 to exclude large particles.

A conduit 8 extends horizontally from the intake 6 toward the oppositeend of the kiln, agreater or less distance, according to requirements.'While the conduit illustrated is perhaps two-thirds the lengthof thekiln, obviously it might be much shorter or even longer.

The heated air within the kiln naturally rises from the heating systemand moves toward the green end where there is less heat and moremoisture, as indicated by the arrows. This air is sucked through theintake 6 and on beingre-heated and re-conditioned, issues from the openend iofthe conduit-and rises through the heating system into the dryingroom A above. Its passage through the conduit is usually facilitated andaccelerated by some artificial means such as is illustrated by jets 9and 10, of steam or compressed air or ventilating fans (not shown) mightbe employed When jets are employed they are usually located at somedistance apart and the location within the conduit is, of course,subject to change so I to suit the conditions. These jets are suppliedfrom a pipe 11 "which has a valve 12. for controlling the two or any,number of jets simultaneously and valves'l3 and 14 are provided as'ameans for cutting out any one of. these jets, or if there should be alarge number of them, several of them. The.

for humidizing and conditioning the air as it is drawn into the intake.The steam supply to this pipe 18 is controlled by a valve.

19 which may be operated by hand or mechanically controlled.

hand valve 22 controls the supply A jet 20 for compressed air or steamis located in the outer end of each of these conduits 16 for creating asuction or partial vacuum in the air intake 15 to cause the air from theextreme dry end of the kiln to flow downwardly into the intake, afterwhichit is discharged through the perforations 17 after beingre-conditioned, upwardly into the kiln above as shown by the arrows atthe right-hand end of the kiln in Figure 1. A pipe 21 supplies thesenozzles and a for the nozzles 20. e The foregoing mechanism serves as anaccelerator for the circulating air at the dry end of the kiln and afterre-conditioning it keeps it moving upwardly through the material and.onward toward the greenend in the natural course of circulation;

Humidity spray pipes 23 may be employed wherever most needed. We haveillustrated two ofthese only, One at the top of the gi'eenend andtheother at the bottom of the dry end. These may be arranged in any way toassist in giving a universal humidity condition and they. may beregulated by hand control or control regulators. Thus a. constant andsubstantially uniform agitation of air is in progress throughout theoperation of the kiln and this in the natural course of movement of theair, with the result that we attain uniformity of temperatures andhumidity throughout the entire'interior of the kiln, but at the sametime with the ability to add to or subtract from,

and otherwise control, the heat, humidity and circulation by the propermanipulation of the various valves. In other words, we attain perfectcontrol of all of these ele' ments or factors.

It will be observed that in the operation of this kiln no fresh air isadmitted from the outside, the present invention being a means or systemof circulation confined to the circulation and re-circulation andconditioning of air wholly inside of the kiln.

In the progressive action of this kiln, advantage is taken of existingnatural conditions, and first among these it might be mentioned that thelumber or material being treated is progressively being denuded of itsmoisture content by the very natureof things. That is to say, the greenlumber is placed in the wet end of the kiln, and the last preceding loadis moved on into the QneXt zone or area in a slightly dry condition, andthe one preceding it is moved forward in a still drier condition, aswith the other loads ahead, as the completelycured load is removed atthe dry end. Each load occupies a zone of its own, as it were. The airfrom the more highly heated or dry end, where the curing isapproachingcompletion or is completed, naturally flows in a direction opposite fromthe progressive movement of the various loadsof lumber or. materialbeing treated, toward the denser or less highly heated green end of thekiln, and to facilitate this natural movement of the air, the heated airis accelerated or boosted in the direction of its natural course by theV discharge of heated and reconditioned air fromthe conduits at thebottom of the dry end. And, as fast as the air reaches the green end, itis sucked down and around the larger conduit and reheated andconditioned, and returned. Thus, due to the differential in moisturecontent at the two ends of, the

From the foregoing it'will be seen that we get a natural air turn-overin a progressiv-e kiln due to the difference in moisture" content at theopposite endsof the kiln, to-

gether with the heating system, thus pro viding a self-regiilatingmeansof control ing the humidity throughout the kiln as long asnioist steamis liberated at any one point. This natural air turn-over tends to givea constant point of precipitation which is the desideratum in anyprogressive operation.

This condition is facilitated by a gradient of heat between the two endsof the,

kiln. This gives a differential in density.

With these various conditions wedirect and control, re-condition,re-circulate, and. 'ac

celerate the movement of the air currentsin their natural cycles ofmovement through.

the kilns,thus attaining a high-degree of uniformity ofheat and humiditythroughout, with the result that the curing opera tion is facilitatedand the product treated is uniformly cured.

We claim:

1. A kiln of the character described' including a drying chamber, aheating system,

humidizers, air intakes at opposite ends, a. return conduit leading fromone air intake and discharging Well into the interiorfof the kiln, aplurality'of air conduits extend ing inwardly from the intake at theopposite end of the kiln and discharging upwardly into the kiln, andmeans located within the several conduits for creating a suction of airfrom the kiln into the. air intakes, and for causing its dischargetherefrom, into the kiln, and valve mechanism for regulating andcontrolling the passage of airthrough;

these conduits.

2. A kiln of the characterdescribed in cluding a. drying chamber, aheating system,

humidizers, air intakes at opposite ends, a return conduit leading fromonea r intake and discharging well into theinterior ofthe kiln, aplurality of air conduits extending inwardly from the intake at theopposite end of the kiln and discharging upwardly into the kiln, meanslocated within the several conduits for creating a suction of air fromthe kiln into the air intakes, and for causing its discharge therefrom,into the kiln, valve mechanism for regulating and controlling thepassage of air through these conduits, and humidizing means located atthe intake which supplies the return conduits at the dry end of thekiln.

3. A kiln of the character described including a drying chamber, airconditioning means for said drying chamber, and means for withdrawingair from the green end of the chamber and directing said air toward thedry end of the chamber, discharging the air in the region of the dry endfor natural recirculation toward the green end in a direction oppositeto the movement of the material being treated, and means for causing anauxiliary circulation of air at the dry end.

4. A kiln of thecharacter described ineluding a drying chamber, an airintake extending across the kiln at the green end thereof, and a returnconduit leading from said air intake to the region of the dry end forWithdrawing air from the green end through the conduit and dischargingthe air into the dry end of the chamber for natural recirculation backthrough the kiln in a direction opposite to the. movement of thematerial therethrough.

5. A kiln of the character described including a drying chamber, meansfor conditioning air therein, air intakes approximately at the oppositeends of the kiln, a return conduit leading from one .air intake anddischarging in the region of the dry end, and a relatively short conduitextending inwardly from the other air intake for creating an auxiliarycirculation of air at the dry end. I

In testimony whereof We affix our signatures. I

FRANK CREIGHTON. WILLIAM E. GRAY;

